This invention relates to cephalosporin antibiotics. In particular, it relates to cephalosporin antibiotic compounds substituted in the 3'-position with a isoquinolinium or substituted isoquinolinium group, and in the 7-position with a 2-(aminooxazolyl or aminooxadiazolyl)-2-oximinoacetyl group.
Cephalosporin compounds substituted in the 3'-position with a quaternary ammonium group have been known for some time. For example, cephalosporin C.sub.A (pyridine) was one of the first derivatives of cephalosporin C prepared by Abraham et al. following the discovery of cephalosporin C, Hale, Newton, and Abraham, Biochem. J., 79, 403 (1961).
Cephaloridine, the well-known clinical antibiotic, is the 3'-pyridinium cephalosporin, 7-(.alpha.-thienylacetamido)-3-(pyridinium-1-ylmethyl)-3-cephem-4-carboxyl ate. Recently, Heymes et al., U.S. Pat. No. 4,152,432, describe semi-synthetic cephalosporin antibiotics wherein the 7-position side chain is a 7-[2-(2-(aminothiazol-4-yl)-2-alkoxyiminoacetamido] group and the 3-position substituent is acetoxymethyl. More recently, Takeda, U.K. Patent Specification No. 1,581,854, describes syn-7-[2-(2-aminothiazol-4-yl)-2-methoxyimino]-3-pyridiniummethyl-3-cephem -4-carboxylate. O'Callaghan, et al., in U.S. Pat. No. 4,258,041, describe 7-[2-(2-aminothiazole-4-yl)-2-oximinoacetamido]-3-(pyridinium-1-ylmethyl)- 3-cephem-4-carboxylate antibiotics, and the corresponding compounds wherein the pyridinium group in the 3'-position is substituted with a carbamoyl group.
Because of the continuing need for improved antibiotic therapy in clinical practice, the search continues for broad spectrum antibiotics with greater potency and minimal toxicity. The semi-synthetic cephalosporin antibiotics long have been recognized as broad spectrum antibiotics, and several have achieved clinical importance. Continued research with the cephalosporin antibiotics has centered of late with the development of antibiotics having higher activity against certain gram-negative microorganisms such as pseudomonas and those which produce .beta.-lactamases destructive of .beta.-lactam antibiotics.